1. Field of the Invention
The present invention relates to an electronic device, a method of manufacturing the same, and a camera.
2. Description of the Related Art
In the manufacture of an electronic device such as a solid-state image sensing device or display device, a photolithography technique is applied to form the pattern of a blue filter, black filter, or the like. The blue filter, black filter, or the like is made of a material having low transmittance at many wavelengths of light. In alignment in the photolithography process for forming the pattern of a blue filter, black filter, or the like, an alignment mark under a film (that is, a film to be patterned) for forming the blue filter, black filter, or the like needs to be detected. However, this film has low transmittance for light used for alignment (to be referred to as alignment light hereinafter). Hence, the intensity of light reflected by the alignment mark becomes weak, and it is difficult to detect the alignment mark.
Japanese Patent Laid-Open No. 11-211908 discloses a method of forming a blue filter after forming a red filter. In this method, a red alignment mark is formed when forming a red filter, and alignment is performed with red alignment light using the red alignment mark when forming a blue filter. Japanese Patent Laid-Open No. 2007-004082 discloses a method of selectively removing a material having low light transmittance on an alignment mark and then detecting the alignment mark.
In the method disclosed in Japanese Patent Laid-Open No. 11-211908, a red alignment mark is formed when forming a red filter, and alignment is performed using the red alignment mark when forming a blue filter. Thus, a misalignment between an alignment mark under the red filter and the red alignment mark becomes an error factor in alignment for forming a blue filter.
In the method disclosed in Japanese Patent Laid-Open No. 2007-004082, a material having low light transmittance on an alignment mark is removed by the photolithography technique, so a process such as formation of a photoresist mask pattern for photolithography is necessary. That is, the technique disclosed in Japanese Patent Laid-Open No. 2007-004082 increases the number of processes and the cost.